Fifty-nine patients have undergone operation for fibrous subaortic stenosis. There were four (6.8%) early deaths. Forty-three of these patients have been followed for up to 24 years (mean 10.6) after operation; of 37 patients undergoing early postoperative cardiac catheterizations, 70% had satisfactory relief of obstruction. Of the 32 late survivors 75% are asymptomatic. Actuarial survival is 80 + 6% at ten years. However, late survival free of adverse events, including residual obstruction, significant aortic regurgitation, endocarditis, complete heart block or reoperation is 27 + 7% at ten years.